U.S. patent number 8,574,918 [Application Number 13/055,720] was granted by the patent office on 2013-11-05 for sample injector, sample injecting method, and liquid chromatograph.
This patent grant is currently assigned to Shiseido Company, Ltd.. The grantee listed for this patent is Aya Hirayama, Kazuhiko Mibayashi, Masashi Mita, Osamu Shirota. Invention is credited to Aya Hirayama, Kazuhiko Mibayashi, Masashi Mita, Osamu Shirota.
United States Patent |
8,574,918 |
Hirayama , et al. |
November 5, 2013 |
Sample injector, sample injecting method, and liquid
chromatograph
Abstract
A sample injection part connected to a column to inject a sample
into the column; a sample injection needle attachable to the sample
injection part; a sample suction part connectable to the sample
injection needle and configured to cause a predetermined amount of
the sample to be drawn by suction into the sample injection needle
upon connecting to the sample connection needle; a mobile phase
supply part configured to supply the column with a mobile phase; a
first switching valve for selectively connecting the sample
injection needle to one of the sample suction part and the mobile
phase supply part; and a second switching valve, including the
sample injection part, for supplying the sample and the mobile
phase to the column via the sample injection needle in the case of
having the sample injection needle attached to the sample injection
part and for supplying the mobile phase to the column via the first
switching valve in the case of having the sample injection needle
removed from the sample injection part are included.
Inventors: |
Hirayama; Aya (Kanagawa,
JP), Shirota; Osamu (Kanagawa, JP), Mita;
Masashi (Tokyo, JP), Mibayashi; Kazuhiko (Kyoto,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Hirayama; Aya
Shirota; Osamu
Mita; Masashi
Mibayashi; Kazuhiko |
Kanagawa
Kanagawa
Tokyo
Kyoto |
N/A
N/A
N/A
N/A |
JP
JP
JP
JP |
|
|
Assignee: |
Shiseido Company, Ltd. (Tokyo,
JP)
|
Family
ID: |
41610398 |
Appl.
No.: |
13/055,720 |
Filed: |
July 28, 2009 |
PCT
Filed: |
July 28, 2009 |
PCT No.: |
PCT/JP2009/063400 |
371(c)(1),(2),(4) Date: |
January 25, 2011 |
PCT
Pub. No.: |
WO2010/013698 |
PCT
Pub. Date: |
February 04, 2010 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20110120213 A1 |
May 26, 2011 |
|
Foreign Application Priority Data
|
|
|
|
|
Aug 1, 2008 [JP] |
|
|
2008-200063 |
|
Current U.S.
Class: |
436/161; 210/656;
73/61.56; 210/198.2; 422/70; 73/61.55 |
Current CPC
Class: |
G01N
30/20 (20130101); G01N 35/1097 (20130101); G01N
30/16 (20130101); G01N 30/24 (20130101); G01N
35/1004 (20130101) |
Current International
Class: |
G01N
30/16 (20060101); G01N 30/18 (20060101) |
Field of
Search: |
;422/70,89
;73/61.55,61.56,23.35-23.42 ;210/198.2,656 ;96/101-107 ;95/89
;436/161 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
1843153 |
|
Oct 2007 |
|
EP |
|
1535441 |
|
Dec 1978 |
|
GB |
|
2003-215118 |
|
Jul 2003 |
|
JP |
|
2005-031012 |
|
Feb 2005 |
|
JP |
|
2006-201121 |
|
Aug 2006 |
|
JP |
|
3 129218 |
|
Feb 2007 |
|
JP |
|
2008-164498 |
|
Jul 2008 |
|
JP |
|
WO 2008-029422 |
|
Mar 2008 |
|
WO |
|
Other References
Extended European Search Report mailed Oct. 14, 2011. cited by
applicant.
|
Primary Examiner: Ludlow; Jan
Attorney, Agent or Firm: IPUSA, PLLC
Claims
The invention claimed is:
1. A sample injector, comprising: a sample injection part connected
to a column to inject a sample into the column; a sample injection
needle attachable to the sample injection part; a sample suction
part connectable to the sample injection needle and configured to
cause a predetermined amount of the sample to be drawn by suction
into the sample injection needle upon connecting to the sample
connection needle; a mobile phase supply part configured to supply
the column with a mobile phase; a first switching valve for
selectively connecting the sample injection needle to one of the
sample suction part and the mobile phase supply part; and a second
switching valve, including the sample injection part, for supplying
the sample and the mobile phase to the column via the sample
injection needle in a case of having the sample injection needle
attached to the sample injection part and for supplying the mobile
phase to the column via the first switching valve in a case of
having the sample injection needle removed from the sample
injection part, the second switching valve including a first path
for supplying the sample and the mobile phase to the column; and a
second path for supplying the mobile phase to the first path in the
case of having the sample injection needle removed from the sample
injection part, wherein the second path is configured to be closed
by the sample injection needle inserted through the sample
injection part into the first path in the case of having the sample
injection needle attached to the sample injection part.
2. The sample injector as claimed in claim 1, wherein the second
switching valve comprises: an insertion and holding member
configured to have the sample injection needle inserted thereinto
and hold the inserted sample injection needle, wherein the
insertion and holding member is configured to close the first path
in a case of having the sample injection needle removed from the
insertion and holding member.
3. The sample injector as claimed in claim 2, wherein the insertion
and holding member comprises: a moving part for moving an insertion
part, into which the sample injection needle is to be inserted, to
close the first path, wherein the first switching valve is
configured to perform switching so as to prevent a flow of the
mobile phase into the column from being interrupted by closing the
first path by the moving part.
4. A sample injecting method for injecting a sample into a column
using a sample injector including a sample injection part connected
to the column to inject the sample into a column; a sample
injection needle attachable to the sample injection part; a sample
suction part connectable to the sample injection needle and
configured to cause a predetermined amount of the sample to be
drawn by suction into the sample injection needle upon connecting
to the sample connection needle; a mobile phase supply part
configured to supply the column with a mobile phase; a first
switching valve for selectively connecting the sample injection
needle to one of the sample suction part and the mobile phase
supply part; and a second switching valve, including the sample
injection part, for supplying the sample and the mobile phase to
the column via the sample injection needle in a case of having the
sample injection needle attached to the sample injection part and
for supplying the mobile phase to the column via the first
switching valve in a case of having the sample injection needle
removed from the sample injection part, the sample injecting method
comprising: a first mobile phase supplying step of connecting the
sample injection needle and the mobile phase supply part through
path switching performed by the first switching valve and supplying
the mobile phase from the sample injection needle to the column in
the case of having the sample injection needle attached to the
sample injection part; a sample suction step of connecting the
sample injection needle and the sample suction part through the
path switching performed by the first switching valve and causing
the sample to be drawn by suction into the sample injection needle;
and a second mobile phase supplying step of supplying the column
with the mobile phase from the mobile phase supply part through
path switching performed by the first switching valve and the
second switching valve while causing the sample to be drawn by
suction into the sample injection needle by the sample suction
step, wherein the second switching valve includes a first path for
supplying the sample and the mobile phase to the column and a
second path for supplying the mobile phase to the first path in the
case of having the sample injection needle removed from the sample
injection part, and the second path is closed by the sample
injection needle inserted through the sample injection part into
the first path in the case of having the sample injection needle
attached to the sample injection part.
5. The sample injecting method as claimed in claim 4, further
comprising: a closing step of closing the first path in a case of
having the sample injection needle removed from an insertion part
of an insertion and holding member, using the insertion and holding
member provided in the second switching valve for having the sample
injection needle inserted thereinto and holding the inserted sample
injection needle.
6. The sample injecting method as claimed in claim 5, wherein the
second mobile phase supplying step supplies the mobile phase to the
first path via the second path when the first path is closed.
7. The sample injecting method as claimed in claim 5, wherein: the
closing step closes the first path by causing the insertion part of
the insertion and holding member configured to have the sample
injection needle inserted thereinto to be moved by a moving part,
and the second mobile phase supplying step causes the first
switching valve to perform switching so as to prevent a flow of the
mobile phase into the column from being interrupted by closing the
first path by the moving part.
8. A liquid chromatograph, comprising: a sample injector, the
sample injector including a sample injection part connected to a
column to inject a sample into the column; a sample injection
needle attachable to the sample injection part; a sample suction
part connectable to the sample injection needle and configured to
cause a predetermined amount of the sample to be drawn by suction
into the sample injection needle upon connecting to the sample
connection needle; a mobile phase supply part configured to supply
the column with a mobile phase; a first switching valve for
selectively connecting the sample injection needle to one of the
sample suction part and the mobile phase supply part; and a second
switching valve, including the sample injection part, for supplying
the sample and the mobile phase to the column via the sample
injection needle in a case of having the sample injection needle
attached to the sample injection part and for supplying the mobile
phase to the column via the first switching valve in a case of
having the sample injection needle removed from the sample
injection part, the second switching valve including a first path
for supplying the sample and the mobile phase to the column; and a
second path for supplying the mobile phase to the first path in the
case of having the sample injection needle removed from the sample
injection part, wherein the second path is configured to be closed
by the sample injection needle inserted through the sample
injection part into the first path in the case of having the sample
injection needle attached to the sample injection part.
Description
TECHNICAL FIELD
The present invention relates to sample injectors, sample injecting
methods, and liquid chromatographs, and particularly to a sample
injector, a sample injecting method, and a liquid chromatograph for
preventing the occurrence of carryover and improving detection
accuracy with a relatively inexpensive configuration.
BACKGROUND ART
Conventionally, liquid chromatographs include a reservoir to store
a mobile phase (elution solvent), a pump to supply the mobile phase
from the reservoir, a sample injector to inject a sample together
with the mobile phase into a tubing leading to a column, the column
filled with a packing material for separating components in the
sample, an oven to keep the column at a constant temperature, and a
detector to detect the separated components in the sample. Of
these, the sample injector is so structured as to attach a sample
injection needle that has drawn in the sample by suction to a
sample injection port (sample injection part) and to inject the
sample together with the mobile phase into the tubing via a
switching valve.
In recent years, with improvement in the detection sensitivity of
liquid chromatographs, a phenomenon called carryover has become a
problem. The carryover, which is a phenomenon that an earlier
measured sample remains in a liquid chromatograph to present such a
detection result as if the substance were present in a currently
measured sample, degrades the reliability of analysis results. The
carryover is caused by the mixture of a residual sample at the time
of injecting the next sample, the residual sample having adhered to
a metal and/or a resin inside a sample injector at the time of
injecting the sample together with a mobile phase into a tubing and
remained.
Therefore, in order to ensure reduction of the carryover, a
technique has been proposed that provides two injection needles and
attaches a first one of the sample injection needles that has drawn
in a sample by suction to a sample injection port, thereby allowing
the sample to be supplied to a column without intervention of a
switching valve, thus preventing the sample from remaining in the
switching valve as it does conventionally and making it possible to
sufficiently reduce the carryover. (For example, see Patent
Document 1.)
In the apparatus provided with two injection needles illustrated in
Patent Document 1, a sample is injected through the process of
disconnecting a first sample injection needle in a mobile phase
supplying state where the first sample injection needle is
connected to an injection part, and connecting a second sample
injection needle retaining the sample to the injection and causing
a mobile phase to restart flowing into a column.
PRIOR ART DOCUMENT
Patent Document
[Patent Document 1] Japanese Laid-Open Patent Application No.
2006-201121
DISCLOSURE OF THE INVENTION
Problems to Be Solved by the Invention
In the above-described conventional technique, it is possible to
prevent the occurrence of carryover, while the two sample injection
needles are provided and a complicated control function for
controlling them individually may be separately needed. Further, in
the sample injection process using the two sample injection
needles, a certain period of time is necessary to switch the
needles, and the flow of the mobile phase into the column is
interrupted during this state change to cause a variation in the
pressure inside the column, which is not preferable for stable
analysis. Further, a special consideration may be necessary as to a
leak of liquid at the time of detaching the two needles.
For the above-described reasons, it is preferable to prevent the
occurrence of carryover and improve detection accuracy with a
relatively inexpensive configuration in the sample injection
process.
Accordingly, the present invention has been made in view of the
above-described problems, and has an object of providing a sample
injector, a sample injecting method, and a liquid chromatograph for
preventing the occurrence of carryover and improving detection
accuracy with a relatively inexpensive configuration.
Means for Solving the Problems
In order to solve the above-described problems, the present
invention adopts means for solving the problems with the following
features.
The present invention is characterized by including a sample
injection part connected to a column to inject a sample into the
column; a sample injection needle attachable to the sample
injection part; a sample suction part connectable to the sample
injection needle and configured to cause a predetermined amount of
the sample to be drawn by suction into the sample injection needle
upon connecting to the sample connection needle; a mobile phase
supply part configured to supply the column with a mobile phase; a
first switching valve for selectively connecting the sample
injection needle to one of the sample suction part and the mobile
phase supply part; and a second switching valve, including the
sample injection part, for supplying the sample and the mobile
phase to the column via the sample injection needle in a case of
having the sample injection needle attached to the sample injection
part and for supplying the mobile phase to the column via the first
switching valve in a case of having the sample injection needle
removed from the sample injection part.
This makes it possible to prevent the occurrence of carryover and
to improve detection accuracy with a relatively inexpensive
configuration.
Further, the second switching valve is characterized by including
an insertion and holding member configured to have the sample
injection needle inserted thereinto and hold the inserted sample
injection needle; and a first path for supplying the sample and the
mobile phase to the column, wherein the insertion and holding
member is configured to close the first path in a case of having
the sample injection needle removed from the insertion and holding
member.
This makes it possible to close a path with a simple configuration.
This makes it possible to limit the passage of the sample and to
prevent carryover.
The present invention is further characterized by including a
second path for supplying the mobile phase to the first path in a
case of having the first path closed.
This enables continuous supply of the mobile phase to the column.
Further, this configuration makes it possible to limit the passage
of the sample and to prevent carryover.
Further, the insertion and holding member is characterized by
including a moving part for moving an insertion part, into which
the sample injection needle is to be inserted, to close the first
path, wherein the first switching valve is configured to perform
switching so as to prevent a flow of the mobile phase into the
column from being interrupted by closing the first path by the
moving part.
This makes it possible to ensure closure with a simple mechanism.
Further, the switching of the first switching valve, which occurs
substantially simultaneously with this closure, allows the mobile
phase to flow into the column without a substantial interruption.
Further, it is possible to prevent carryover.
Further, the present invention, which is a sample injecting method
for injecting a sample into a column using a sample injector
including a sample injection part connected to the column to inject
the sample into the column; a sample injection needle attachable to
the sample injection part; a sample suction part connectable to the
sample injection needle and configured to cause a predetermined
amount of the sample to be drawn by suction into the sample
injection needle upon connecting to the sample connection needle; a
mobile phase supply part configured to supply the column with a
mobile phase; a first switching valve for selectively connecting
the sample injection needle to one of the sample suction part and
the mobile phase supply part; and a second switching valve,
including the sample injection part, for supplying the sample and
the mobile phase to the column via the sample injection needle in a
case of having the sample injection needle attached to the sample
injection part and for supplying the mobile phase to the column via
the first switching valve in a case of having the sample injection
needle removed from the sample injection part, is characterized by
including a first mobile phase supplying step of connecting the
sample injection needle and the mobile phase supply part through
path switching performed by the first switching valve and supplying
the mobile phase from the sample injection needle to the column in
the case of having the sample injection needle attached to the
sample injection part; a sample suction step of connecting the
sample injection needle and the sample suction part through the
path switching performed by the first switching valve and causing
the sample to be drawn by suction into the sample injection needle;
and a second mobile phase supplying step of supplying the column
with the mobile phase from the mobile phase supply part through
path switching performed by the first switching valve and the
second switching valve while causing the sample to be drawn by
suction into the sample injection needle by the sample suction
step.
This makes it possible to close a path with a simple configuration.
This makes it possible to limit the passage of the sample and to
prevent carryover.
The present invention is further characterized by including a
closing step of closing a first path for supplying the sample and
the mobile phase to the column in a case of having the sample
injection needle removed from an insertion part of an insertion and
holding member, using the insertion and holding member provided in
the second switching valve for having the sample injection needle
inserted thereinto and holding the inserted sample injection
needle.
This makes it possible to close a path with a simple configuration.
This makes it possible to limit the passage of the sample and to
prevent carryover.
Further, the second mobile phase supplying step is characterized by
supplying the mobile phase to the first path via a second path when
the first path is closed.
This enables continuous supply of the mobile phase to the column.
Further, this configuration makes it possible to limit the passage
of the sample and to prevent carryover.
Further, the closing step is characterized by closing the first
path by causing an insertion part provided in the insertion and
holding member and configured to have the sample injection needle
inserted thereinto to be moved by a moving part, and the second
mobile phase supplying step is characterized by causing the first
switching valve to perform switching so as to prevent a flow of the
mobile phase into the column from being interrupted by closing the
first path by the moving part.
This makes it possible to ensure closure with a simple mechanism.
Further, the switching of the first switching valve, which occurs
substantially simultaneously with this closure, allows the mobile
phase to flow into the column without a substantial interruption.
Further, it is possible to prevent carryover.
Further, the present invention is a liquid chromatograph
characterized by including a sample injector including a sample
injection part connected to a column to inject a sample into a
column; a sample injection needle attachable to the sample
injection part; a sample suction part connectable to the sample
injection needle and configured to cause a predetermined amount of
the sample to be drawn by suction into the sample injection needle
upon connecting to the sample connection needle; a mobile phase
supply part configured to supply the column with a mobile phase; a
first switching valve for selectively connecting the sample
injection needle to one of the sample suction part and the mobile
phase supply part; and a second switching valve, including the
sample injection part, for supplying the sample and the mobile
phase to the column via the sample injection needle in a case of
having the sample injection needle attached to the sample injection
part and for supplying the mobile phase to the column via the first
switching valve in a case of having the sample injection needle
removed from the sample injection part.
This makes it possible to provide a liquid chromatograph capable of
preventing the occurrence of carryover to be improved in detection
accuracy while maintaining a relatively inexpensive
configuration.
Effects of the Invention
According to the present invention, it is possible to provide a
sample injector, a sample injecting method, and a liquid
chromatograph that prevent the occurrence of carryover to be
improved in detection accuracy with a relatively inexpensive
configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating a liquid chromatograph in an
embodiment.
FIG. 2 is a perspective view illustrating a sample injector in this
embodiment.
FIG. 3A is a (first) diagram for illustrating a specific example of
a direct injection valve.
FIG. 3B is a (second) diagram for illustrating the specific example
of the direction injection valve.
FIG. 4A is a (first) diagram illustrating a device configuration of
the direct injection valve.
FIG. 4B is a (second) diagram illustrating the device configuration
of the direct injection valve.
FIG. 4C is a (third) diagram illustrating the device configuration
of the direct injection valve.
FIG. 5 is a diagram illustrating the state of the sample injector
at a standby time (or during analysis) in this embodiment.
FIG. 6 is a diagram illustrating the state of the sample injector
at a sample taking time in this embodiment.
FIG. 7 is a diagram illustrating the state of the sample injector
at the time of preliminary cleaning of the sample injection needle
in this embodiment.
FIG. 8 is a diagram illustrating the state of the sample injector
at the time of ultrasonic cleaning of the sample injection needle
in this embodiment.
FIG. 9 is a diagram illustrating the state of the sample injector
at a sample injecting time in this embodiment.
FIG. 10 is a diagram illustrating the state of the sample injector
at the time of replacing ultrasonic cleaning port wash liquid (or
during analysis) in this embodiment.
FIG. 11 is a graph illustrating detection results in a
detector.
DESCRIPTION OF EMBODIMENT
A description is given below, using drawings, of an embodiment in
which a sample injector, a sample injecting method, and a liquid
chromatograph are suitably implemented.
[General Configuration of Liquid Chromatograph]
First, a description is given, using a drawing, of a general
configuration of a liquid chromatograph having a sample injector in
the present invention. FIG. 1 is a diagram illustrating a general
configuration of a liquid chromatograph in this embodiment.
A liquid chromatograph 10 illustrated in FIG. 1 is configured to
have a reservoir (eluent bath) 11, a pump (mobile phase supply
part) 12, a sample injector 13, a column oven 14, and a detector
15.
The reservoir 11 stores a mobile phase (elution solvent) that is an
eluent. The pump 12 continuously flows the mobile phase stored in
the reservoir 11 into the sample injector 13.
The sample injector 13 injects a sample and the mobile phase into a
tubing 16 to the column oven 14, etc. A description is given below
of a specific apparatus configuration of the sample injector 13 and
a specific sample injecting method, etc., in the present
invention.
The column oven 14 keeps at a constant temperature a separation
column 17 filled with a packing material for separating components
in the sample injected from the tubing 16. The detector 15 detects
separated components (chemical substances and so on). In order to
stabilize measurement, it is preferable that the mobile phase be
constantly supplied from the reservoir 11 to the column 17 via the
sample injector 13 by the pump 12.
In the present invention, the liquid chromatograph is not limited
in configuration to the above-described one, and, for example, a
degasser to degas the mobile phase may be provided between the
reservoir (eluent bath) 11 and the pump 12.
[Sample Injector 13: Functional Configuration]
Next, a description is given, using a drawing, of a functional
configuration of the sample injector 13 applied to the liquid
chromatograph 10 as described above, etc. FIG. 2 is a diagram
illustrating a functional configuration of a sample injector in
this embodiment. The sample injector 13 illustrated in FIG. 2 is
configured to have a sample injection needle 21, a syringe (sample
suction part) 22, a wash liquid pump 23, a valve 24, a sample
container 25, an injection valve (first switching valve) 26, a wash
liquid container 27, a cleaner 28, a direct injection valve (second
switching valve) 29, and a needle moving part 30.
The sample injection needle 21 is connectable to the syringe 22 via
the injection valve 26 and the valve 24. Further, the sample
injection needle 21 is also connectable to the wash liquid pump 23
via the injection valve 26.
Here, upon connection of the sample injection needle 21 to the
syringe 22 through path switching performed by the valve 24, a
sample may be drawn into by suction and discharged from the sample
injection needle 21 by the pulling and pushing of the syringe
22.
Upon connection of the sample injection needle 21 to the wash
liquid pump 23 via the injection valve 26 through path switching
performed by the injection valve 26, wash liquid (for example,
water or the like) inside the wash liquid container 27 is supplied
to the sample injection needle 21.
The valve 24 causes wash liquid delivered from the wash liquid
container 27 by the wash liquid pump 23 to be supplied selectively
to the cleaner 28 or the sample injection needle 21. Specifically,
the valve 24 has, for example, three ports P1 through P3, and can
selectively connect two of them.
Here, the syringe 22 and the injection valve 26 are connected to a
single port (for example, P3) of the valve 24, so that the syringe
22 and the injection valve 26 are constantly connected. The valve
24 is also allowed to make the ports P1 through P3 unconnected to
one another.
The sample container 25 has a sample stored inside. A predetermined
necessary amount of the sample stored in the sample container 25 is
drawn in by suction by the sample injection needle 21, and is
discharged to a sample injection part (direction injection port)
provided in the direct injection valve 29.
The injection valve 26 is, for example, configured to have six
ports (for example, a high-pressure six-way valve). Further, the
injection valve 26 has the pump 12, the sample injection needle 21,
the valve 24, the cleaner 28, and the direction injection valve 29
connected to five of the six ports. Further, the injection valve 26
is configured to switch multiple preset connections as
required.
The wash liquid container 27 has wash liquid stored inside and is
connected to the wash liquid pump 23. The wash liquid stored in the
wash liquid container 27 has a predetermined amount necessary for
cleaning drawn in by suction by the wash liquid pump 23 to be
pumped to the valve 24.
The cleaner 28 is, for example, configured to include a cleaning
part, an ultrasonic vibrator, a waste liquid port, and a waste
liquid tubing. Further, upon connection to the wash liquid pump 23
through path switching performed by the valve 24, the cleaner 28 is
supplied with wash liquid from the wash liquid container 27. A
surplus of the wash liquid over a predetermined amount flows into
the waste liquid port to be discharged outside as waste liquid from
the waste liquid tubing connected to the waste liquid port.
Further, upon insertion of the sample injection needle 21 into the
cleaner 28, the cleaner 28 cleans the sample injection needle 21 of
an adhered sample. The cleaner 28 has the function of preventing
the occurrence of carryover by this. Further, the cleaner 28, which
is provided with an ultrasonic vibrator, is configured to allow
ultrasonic cleaning of the sample injection needle 21. This makes
it possible to improve a cleaning effect on the sample injection
needle 21 and to further ensure prevention of the occurrence of
carryover.
The direct injection valve 29, which is a feature of the present
invention, is a mechanism for injecting a sample and a mobile phase
into the column 17 provided in the column oven 14. The direct
injection valve 29 is provided with a sample injection part (direct
injection port). The sample injection part is connected to the
separation column 17. That is, in the sample injector 13 in this
embodiment, the sample injection part is completely separate from
and independent of the injection valve 26. Accordingly, as a result
of the sample injection needle 21 that has drawn in a sample by
suction being attached to the sample injection part and discharging
the sample to the sample injection part, this sample is delivered
to the column 17 with a flow of a mobile phase without going
through the injection valve 26.
Further, the direct injection valve 29 has the mechanism of
delivering only a mobile phase to the column 17 by switching paths
when the sample injection needle 21 has been detached by the needle
moving part 30 and is performing another operation, such as when
taking in a sample. A description is given below of a specific
mechanism of the direct injection valve 29.
The needle moving part 30 moves the sample injection needle 21 to a
predetermined position at a predetermined time based on a preset
sample injection procedure or the like.
As described above, by providing the direct injection valve 29, it
is possible to prevent carryover, which is conventionally caused by
the passage of a sample through the injection valve 26, with a
relatively inexpensive configuration, and to improve detection
accuracy.
[Structure of Direct Injection Valve 29]
Here, a description is given, using drawings, of a specific example
of the above-described direct injection valve 29. FIG. 3A and FIG.
3B are diagrams for illustrating a specific example of the direct
injection valve. FIG. 3A and FIG. 3B illustrate states where the
paths are switched from each other. That is, in this embodiment,
the direct injection valve 29 switches to the connection of FIG. 3A
or FIG. 3B.
The direct injection valve 29 illustrated in FIG. 3A and FIG. 3B is
configured to have an insertion and holding member 31 where the
sample injection needle 21 is to be inserted and held; a base 32; a
first path 33 foamed of a tubing directly connected to the column
17, etc., the first path 33 being failed in the base 32 in order to
cause a sample and a mobile phase to be injected into the column 17
inside the column oven 14; and a second path 34 formed of a tubing,
etc., the second path 34 continuing to inject the mobile phase to
the first path 33 from a side at a predetermined angle
.theta..sub.1 and having the mobile phase flowing in to prevent the
flow of the mobile phase into the column 17 from being interrupted.
As illustrated in FIG. 3A and FIG. 3B, the first path 33 is tapered
in correspondence to the end shape of the sample injection needle
21 in order to facilitate its joining with the sample injection
needle 21.
Here, for the above-described insertion and holding member 31, PEEK
(polyether ether ketone), metal such as stainless steel or
titanium, etc., may be used. Further, the above-described
predetermined angle .theta..sub.1 may be determined to be any angle
based on the positions and the sizes of the first path 33 and the
second path 34 in the device configuration. In the present
invention, the predetermined angle .theta..sub.1 is not limited in
particular, but is preferably, for example, such an angle as to
cause no stagnation in the flow of the mobile phase supplied from
the second path 34 to the first path 33.
As illustrated in FIG. 3A, in the case where the sample injection
needle 21 is inserted through an insertion part 35 of the insertion
and holding member 31 up to a position partway through the first
path 33, the mobile phase from the pump 12 is flown into the first
path 33 via the sample injection needle 21 to be delivered to the
column 17. Further, the sample is also injected from the sample
injection needle 21.
Further, as illustrated in FIG. 3B, with the sample injection
needle 21 removed from the insertion and holding member 31, the
position of the insertion part 35 for the sample injection needle
21 provided in the insertion and holding member 31 is moved by
rotation or sliding to close one end of the first path 33.
The mobile phase from the pump 12 is flown into the first path 33
through the second path 34 in order to prevent the closure of the
one end of the first path 33 from stopping the supply of the mobile
phase to the column 17. This makes it possible to maintain the flow
of the first path 33 and to continuously supply the column 17 with
the mobile phase.
For the direct injection valve 29, in place of one with multiple
paths among ports such as the above-described injection valve 26, a
path switching valve such as a three-way valve may be used.
Here, FIG. 4A through FIG. 4C are diagrams illustrating a device
configuration of the direct injection valve 29. FIG. 4A illustrates
the direct injection valve 29 and a drive part (moving part) 41 for
causing the direct injection valve 29 to operate. FIG. 4B is a
bottom side view of FIG. 4A. FIG. 4C is a diagram illustrating the
sample injection needle 21 detached from the insertion and holding
member 31.
In the case illustrated in FIG. 4A through FIG. 4C, the drive part
41 for rotating the insertion and holding member 31 of the direct
injection valve 29 is provided. For example, a motor or the like
may be used for the drive part 41. Further, the insertion and
holding member 31 of the direct injection valve 29 may be rotated
by, for example, up to a predetermined angle .theta..sub.2 about an
axis by providing the insertion and holding member 31 of the direct
injection valve 29 with a turning force from the drive part through
a belt member 42.
Thereby, when the sample injection needle 21 is pulled out as
illustrated in FIG. 4C, it is possible to make a needle insertion
path 43, provided at a position offset from the axis of rotation of
the insertion and holding member 31, and the first path 33
unconnected and to close the one end of the first path 33 with the
bottom surface of the insertion and holding member 31 by moving the
insertion and holding member 31 by the predetermined angle
.theta..sub.2 in a predetermined direction with the belt member 42
as illustrated in FIG. 4B. This results in the above-described
state as illustrated in FIG. 3B. Further, in the case of inserting
the sample injection needle 21, it is possible to supply the column
17 with the sample and the mobile phase by causing the drive part
41 to rotate the insertion and holding member 31 through the belt
member 42 to connect the needle insertion path 43 and the first
path 33 and further inserting the sample injection needle 21 as
illustrated in FIG. 3A described above.
In this embodiment, the insertion and holding member 31 may have
multiple needle insertion paths (three needle insertion paths 43-1
through 43-3 in the case of FIG. 4B). In the case where multiple
needle insertion paths are provided, any of the paths and the first
path 33 may be connected. This makes it possible to further improve
detection accuracy by using different needle insertion paths 43
depending on the kind of the sample, etc.
Further, in the above-described embodiment illustrated in FIG. 4A
through FIG. 4C, a case is illustrated where the needle insertion
path 43 is moved by the rotation of the insertion and holding
member 31, caused by the drive part 41 using the belt member 42, so
as to close one end of the first path 33. However, the present
invention is not limited to this, and the one end of the first path
33 may be closed by, for example, moving the needle insertion path
43 by causing the insertion and holding member 31 to slide by a
moving part.
[Sample Injecting Method Using Sample Injector 13]
Next, a specific description is given, with reference to FIG. 5
through FIG. 10, of a sample injecting method using the sample
injector 13 in this embodiment. FIG. 5 through FIG. 10, which
illustrate operating states of a sample injection procedure used in
this embodiment, illustrate states at a standby time (during
analysis), at a sample taking time, at a time of preliminary
cleaning of the sample injection needle, at a time of ultrasonic
cleaning of the sample injection needle, at a sample injecting
time, and at a time of replacing ultrasonic cleaning port wash
liquid (during analysis), respectively.
To be specific, FIG. 5 is a diagram illustrating the state of the
sample injector at a standby time (or during analysis) in this
embodiment. FIG. 6 is a diagram illustrating the state of the
sample injector at a sample taking time in this embodiment. FIG. 7
is a diagram illustrating the state of the sample injector at the
time of preliminary cleaning of the sample injection needle in this
embodiment. FIG. 8 is a diagram illustrating the state of the
sample injector at the time of ultrasonic cleaning of the sample
injection needle in this embodiment. Further, FIG. 9 is a diagram
illustrating the state of the sample injector at a sample injecting
time in this embodiment. Further, FIG. 10 is a diagram illustrating
the state of the sample injector at the time of replacing
ultrasonic cleaning port wash liquid (or during analysis) in this
embodiment.
In the configuration illustrated in FIG. 5 through FIG. 10, the
injection valve 26 is provided with six ports, of which five are
connected to the pump 12, the sample injection needle 21, the valve
24, the cleaner 28, and the direct injection valve 29. Further, the
valve 24 and the injection valve 26 may switch a connection
indicated by A in the drawings (hereinafter referred to as
Connection State A) and a connection indicated by B in the drawings
(hereinafter referred to as Connection State B). A path indicated
by solid line illustrates an actual connection, and a path
indicated by broken line illustrates a connection that is not
established.
For example, when the injection valve 26 is in Connection State A,
the sample injection needle 21 is connected to the pump 12 via the
injection valve 26, and the valve 24 is connected to a cleaning
part 28a of the cleaner 28 via the injection valve 26. Further,
when the injection valve 26 is in Connection State B, the sample
injection needle 21 is connected to the valve 24 via the injection
valve 26, and the pump 12 is connected to the direct injection
valve 29 via the injection valve 26.
That is, the sample injection needle 21 is caused to connect to the
syringe 22 through path switching performed by the valve 24 and the
injection valve 26, and a sample (sample vial) 51 in the sample
container 25 is drawn into by suction and discharged from the
sample injection needle 21 by the pulling and pushing of the
syringe 22. Further, upon connection of the sample injection needle
21 to the pump 12 through path switching performed by the injection
valve 26, a mobile phase is supplied from the pump 12 to the sample
injection needle 21.
The valve 24 may selectively supply the cleaner 28 or the sample
injection needle 21 with wash liquid pumped by the wash liquid pump
23. Specifically, the valve 24 has the three ports P1 through P3
and may selectively connect two of them. The valve 24 may also
establish no connections among the ports P1 through P3.
Further, each of the syringe 22 and the injection valve 26 is
connected to the port P3 of the valve 24. That is, the syringe 22
and the injection valve 26 are constantly connected.
Further, the cleaner 28 is configured to have the cleaning part
28a, a cleaning part 28b, a waste liquid port 28c, an ultrasonic
vibrator 28d, and a waste liquid tubing 28e. Upon connection to the
wash liquid pump 23 through the switching of the valve 24, the
cleaner 28 is supplied with wash liquid from the wash liquid
container 27. Further, a surplus of the wash liquid over a
predetermined amount flows into the waste liquid port 28c to be
discharged outside as waste liquid from the waste liquid tubing 28e
connected to the waste liquid port 28c. Further, as described
below, by inserting the sample injection needle 21 into the cleaner
28, the exterior wall of the sample injection needle 21 to which
the sample 51 adheres is cleaned. This makes it possible to prevent
the occurrence of carryover.
Further, the cleaner 28 is provided with the ultrasonic vibrator
28d and may perform ultrasonic cleaning on the sample injection
needle 21. This makes it possible to improve a cleaning effect on
the sample injection needle 21 and to further ensure prevention of
the occurrence of carryover.
The tubing 16 connects the direct injection valve 29 and the column
17 inside the column oven 14. That is, the tubing 16 is not
connected to the injection valve 26, and is separate from and
independent of the injection valve 26. Accordingly, as described
below, the sample injection needle 21 that has drawn in the sample
51 in the sample container 25 by suction is attached to the sample
injection part of the direct injection valve 29 of the tubing 16 to
discharge the sample 51 to the sample injection part, so that the
sample 51 flows through the tubing 16 together with a mobile phase
to be supplied to the column 17.
Next, a specific description is given of a sample injecting method
using the sample injector of the present invention. First, as
illustrated in FIG. 5, in a standby state before taking in the
sample 51 (or during analysis), the injection valve 26 is in
Connection State A, and the valve 24 establishes no connections
among the ports P1 through P3. Further, the sample injection needle
21 is moved by the needle moving part 30 and attached to the sample
injection part of the direct injection valve 29. Accordingly, at
the standby state, the mobile phase supplied from the pump 12 is
supplied to the column 17 via the sample injection needle 21 and
the direct injection valve 29.
Next, as illustrated in FIG. 6, at the time of taking in the sample
51 in the sample injection needle 21, the sample injection needle
21 is inserted into the sample container 25 by the needle moving
part 30. Further, the injection valve 26 is switched to Connection
State B, so that the sample injection needle 21 is connected to the
syringe 22 and the pump 12 is connected to the direct injection
valve 29. Accordingly, at the sample taking time, the mobile phase
supplied from the pump 12 is supplied to the column 17 via the
injection valve 26 and the direct injection valve 29. Accordingly,
the mobile phase is constantly supplied to the column 17, so that
it is possible to stabilize measurement.
Further, the sample injection needle 21 is connected to the syringe
22 via the injection valve 26 and the valve 24. Therefore, by
performing suction using the syringe 22, a predetermined amount of
the sample 51 in the sample container 25 is drawn into the sample
injection needle 21. At this point, the amount of suction of the
sample 51 is so determined as to not allow the drawn sample to
enter the injection valve 26. This makes it possible to prevent the
sample 51 from adhering to the inside of the injection valve 26 and
to prevent the occurrence of carryover. In order to increase the
amount of suction of the sample 51, a sample loop for storing a
sample may be provided in the sample injection needle 21.
Next, when the sample taking is completed, the sample injection
needle 21 to which the sample 51 has adhered is cleaned because the
sample 51 adheres to the exterior wall of the sample injection
needle 21. Specifically, the sample injection needle 21 is
subjected to preliminary cleaning and ultrasonic cleaning.
As illustrated in FIG. 7, at the time of subjecting the sample
injection needle 21 to preliminary cleaning, the sample injection
needle 21 is inserted into the cleaning part 28b of the cleaner 28
with the needle moving part 30 while keeping the injection valve 26
in Connection State B. Further, the valve 24 is switched so as to
connect the ports P1 and P2, and wash liquid in the wash liquid
container 27 is supplied to the cleaning part 28b via the wash
liquid pump 23. Accordingly, the wash liquid spouts out into the
cleaning part 28b, so that the exterior wall of the sample
injection needle 21 is preliminarily cleaned. Wash liquid that has
overflowed from the cleaning part 28b is discharged via the waste
liquid port 28c and the waste liquid tubing 28e.
As illustrated in FIG. 8, at the time of subjecting the sample
injection needle 21 to ultrasonic cleaning, the sample injection
needle 21 is inserted into the cleaning part 28a of the cleaner 28
with the needle moving part 30 while keeping the injection valve 26
in Connection State B. Further, the valve 24 is again switched to
the state of no connections among the ports P1 through P3. In this
state, the ultrasonic vibrator 28d is driven to generate ultrasonic
waves, thereby causing ultrasonic vibrations in the wash liquid
with which the cleaning part 28a is loaded so that the exterior
wall of the sample injection needle 21 is ultrasonically
cleaned.
At the time of preliminary cleaning and at the time of ultrasonic
cleaning as well, the mobile phase is supplied from the pump 12 to
the tubing 16 to the column 17 via the injection valve 26 and the
direct injection valve 29.
Next, when the ultrasonic cleaning is completed, the sample 51 that
has been taken in the sample injection needle 21 is supplied to the
column 17 to analyze the sample 51.
As illustrated in FIG. 9, at the time of analyzing the sample 51,
the injection valve 26 switches again to Connection State A from
Connection State B, and the sample injection needle 21 is moved to
be attached to the sample injection part of the direct injection
valve 29 by the needle moving part 30. Further, the sample
injection needle 21 that has drawn in the sample 51 by suction is
connected to the pump 12 through the injection valve 26. As a
result, the sample 51 inside the sample injection needle 21 is
supplied to the column 17 without passing through the injection
valve 26. Further, the sample 51 supplied to the column 17 is
subjected to predetermined separation in the column 17 and is
thereafter sent to the detector 15 and analyzed.
At the time of sample analysis, the wash liquid of the cleaning
part 28a of the cleaner 28 may be replaced. In this case, as
illustrated in FIG. 10, the valve 24 is switched so as to connect
the ports P2 and P3 of the valve 24, and the wash liquid in the
wash liquid container 27 is supplied to the cleaning part 28a via
the valve 24 and the injection valve 26 using the wash liquid pump
23. As a result, the wash liquid contaminated by cleaning the
sample injection needle 21 is discharged via the waste liquid port
28c and the waste liquid tubing 28e, and the cleaning part 28a is
supplied with uncontaminated wash liquid. This makes it possible to
clean the exterior wall of the sample injection needle 21 with more
reliability at the next ultrasonic cleaning time
[Example Detection Results in Detector 15]
Next, a description is given, using a drawing, of detection results
obtained by analysis with the detector 15 using a sample obtained
by the above-described sample injecting method in this
embodiment.
FIG. 11 is a graph illustrating detection results in the detector
15. The graph illustrated in FIG. 11, which is the results of
detection of chlorhexidine carryover under a gradient condition
using the above-described configuration of the sample injector 13,
shows time (MINUTES) on the horizontal axis and absorbance (mABU,
milli-absorbance unit) on the vertical axis.
Further, as analysis conditions, CAPCELL PAK IF manufactured by
Shiseido Co., Ltd., 2.0 mm in inner diameter and 50 mm in length,
was used for the column; (A) 100 mM NaClO.sub.4, 10 mM
NH.sub.4H.sub.2PO.sub.4 (pH 2.6) and (B) acetonitrile were used for
the mobile phase; the gradient condition B % was 30% (0
min).fwdarw.70% (3.0 min).fwdarw.70% (3.5 min).fwdarw.30% (3.6
min); the column oven temperature was 25.degree. C.; the object of
detection was UV 260 nm; the samples were (1) chlorhexidine 1200
ppm and (2) a blank sample; and the amount of injection was 2 .mu.L
each. The results of measuring (2) immediately after (1) are
illustrated.
According to this embodiment, as illustrated in FIG. 11, even when
a blank sample presenting data values as (2) was injected
immediately after the injection of a dense sample presenting data
values as (1), nothing was eluted and no carryover was detected
because sample (1) did not remain in the system at all.
That is, as illustrated in FIG. 11, according to the configuration
of this embodiment, it is possible to prevent the occurrence of
carryover and to improve detection accuracy because of the absence
of contamination although the system (gradient condition) is severe
where a residual sample, however little it may be in amount, is
condensed by the gradient to make carryover easier to observe.
As described above, according to the present invention, it is
possible to provide a sample injector, a sample injecting method,
and a liquid chromatograph for preventing the occurrence of
carryover and improving detection accuracy with a relatively
inexpensive configuration.
A description is given above of a preferred embodiment of the
present invention. The present invention, however, is not limited
to this particular embodiment, and variations and modifications may
be made within the scope of the gist of the present invention
described in Claims.
The present international application claims priority based on
Japanese Patent Application No. 2008-200063, filed on Aug. 1, 2008,
the entire contents of which are incorporated herein by
reference.
DESCRIPTION OF THE REFERENCE NUMERALS
10 liquid chromatograph 11 reservoir (eluent bath) 12 pump 13
sample injector 14 column oven 15 detector 16 tubing 17 column 21
sample injection needle 22 syringe 23 wash liquid pump 24 valve 25
sample container 26 injection valve 27 wash liquid container 28
cleaner 29 direct injection valve 30 needle moving part 31
insertion and holding member 32 base 33 first path 34 second path
41 drive part 42 belt member 43 needle insertion path 51 sample
* * * * *